1. Field of the Invention
This invention relates to the field of tracing continuity in bundles or arrays of electrical conductors in cables and electronic equipment and especially to tracing continuity under conditions where an injected tracer signal is likely to cross into an adjacent conductor by stray or unintended capacitive coupling.
2. Background Information
In the troubleshooting of electronic hardware, it is quite often necessary to find or trace a particular wire in a bundle of wires. Since the color coding of the individual wires in a bundle is not generally unique, one standard procedure now employed is to disassemble a cable or wire bundle far enough to be able to allow the stripping of the insulation of the individual wires. A continually checker is then used to identify individual conductors. The limitations of this approach are that the mechanical and electrical integrity of the wire bundle or cable is comprised by this procedure.
It is preferable to be able to trace electrical conductors, to isolate one particular conductor from a number of other conductors, and to positively identify a conductor in relation to other conductors in close proximity with the least amount of intrusion into the insulation system of the conductors. One type of tracing system is disclosed in U.S. Pat. No. 4,491,785 to Pecukonis. In Pecukonis a shaped waveform is conducted into a conductor such as an outlet of an electrical distribution system. The pulses are alternated with a rest period. The magnitude of the pulses in sufficiently high such that an electromagnetic field is generated adjacent to the conductor at a remote enclosure. The conductor is identified by placing an electromagnetic probe adjacent the conductor and sensing the induced field. Another type of conductor tracer is disclosed in U.S. Pat. No. 4,686,454 also to Pecukonis. In this system a time modulated high frequency signal is added to the modulating frequency such that the waveform injected into the conductor is dc offset during the time of high frequency energy injection. At a remote end of the conductor, the transmitted signal is sensed both electrostatically and electromagnetically to form a composite signal.
There is a need for non-intrusive circuit tracer for identifying a conductor in a bundle especially under conditions where capacitive and inductive cross coupling between conductors tend to cause the tracer signal to cross over to adjacent conductors.
Further there is a need for a circuit tracer wherein the tracer signal can be applied of such low magnitude that terminating electronic circuitry can be left in place during the course of operation of the tracing operation.